Lamont-Doherty Geological Observatory of Columbia University, Palisades, NY10964, U.S.A. and URA CNRS 327, Institut Des Sciences
Total Page：16
File Type：pdf, Size：1020Kb
Quaternary Science Reviews, Vol. 11, pp. 593--601, 1992. 0277-3791/92 $15.00 Printed in Great Britain. All rights reserved. © 1992 Pergamon Press Lid IS CAUSAL ECOLOGICAL BIOGEOGRAPHY A PROGRESSIVE RESEARCH PROGRAM? Denis-Didier Rousseau Lamont-Doherty Geological Observatory of Columbia University, Palisades, NY10964, U.S.A. and URA CNRS 327, Institut des Sciences de l'Evolution, Universit~ Montpellier II, Place Eugdne Bataillon, 34095 Montpellier Cddex 5, France Various spacial and temporal time scales need to be taken into account in the interpretation of biological events. Omission of these aspects can lead to purely descriptive studies of changes in faunal assemblages, which are severely limited in scope. Terrestrial molluscs, which are very sensitive to environmental and climatic changes, provide a good example to illustrate this problem. Using an ecological biogeographic approach, a review of mollusc assemblages from holsteinian tufas in western Europe is presented. The analysis permits the definition of the Lyrodiscus biome, which corresponds t ° a temperate mixed forest community which developed under a particularly warm oceanic climate, and never occurred in Western Europe since that time. are to recognize the diversity of life and to establish the INTRODUCTION hierarchical organization of living organisms. The principle has been much used by botanists and some The new concept of biogeography, by Croizat (1958), palaeontologists, and it has allowed the recognition of associates the evolution of the Earth with that of life. floral and faunal provinces. But within it, two different Croizat replaces a purely descriptive biogeographical concepts can be distinguished (Table 1): ecological approach with a dynamic, analytical, causal process. (ecological descriptive biogeography) and phenetic Biogeographical works applying Croizat's methodology (phenetic descriptive biogeography). (pan-biogeography), or others inspired by it (e.g. First, ecological descriptive biogeography. The pro- vicariance biogeography -- Rosen, 1978) are numer- cess is eclectic and there are two approaches. The ous, but they favour the historical causal approach former makes an inventory of the communities, ana- which led to the recognition and to the analysis of lyzed against environmental controls, and mapped. biotas (historical biological communities). This paper This results in a hierarchical organization of communi- attempts to see if it may be possible to conceive a causal ties (a synecological approach). The latter makes an biogeography during a shorter period, at the scale of inventory of the taxa, case by case, and then maps 'ecological time', and to see if it is possible to integrate them. Their distribution is also analyzed against en- this approach with others. To adapt the title of the vironmental controls. This results in an identification of paper by Craw and Weston (1984) to the present morpho-functional stresses in relation to ecological discussion: is causal ecological (palaeo)biogeography conditions (autecological approach) (Table 1). possible and can it underpin research methodology? In southern and ~vestern Finland, Aho (1984) ex- Hitherto examples of such an approach based on plained the local diversity of freshwater gastropods by invertebrates, and more precisely land snails, are rare variation in water quality. In another context, Shikov despite the endeavour of Solem (1984). Nevertheless, (1984) demonstrated that human activities in the because they are well adapted to their environment, central part of European U.S.S.R. have influenced the land snails are appropriate for illustrating ecological distribution of land snails. The decrease in forest cover (palaeo)biogeography. Examples are presented from leads to some extinction of shade-demanding taxa and the global review of malacology by Solem and van to the spread of snails adapted to open habitats. Bruggen (1984). Second, phenetic biogeography may be quantitative or qualitative. In the former case, similarity indices are AlMS AND SCOPES OF BIOGEOGRAPHY calculated to compare data, to determine a hierarchical organization of distributions, and to determine An analysis of the biogeographical literature, shows (bio)geographical units. In the latter the census of taxa two major philosophical approaches: one is essentially distributions is mapped, and leads to a definition of descriptive, the other causal. A brief review of biogeo- (bio)geographical areas (Table 1). graphy is desirable to distinguish between them, using Andr6 (1984) described 829 stations in Mediterra- the summary of Dommergues and Marchand (in press). nean Spain and France. Computer analysis of 125 species allowed him to distinguish thirteen geographical Descriptive Biogeography groups on the basis of biotic and abiotic variables such Descriptive biogeography is the approach that was as: provinces or departments, chorological and ecologi- widely used by Darwin and his followers. Its main aims cal sectors and vegetation series. 593 594 D.-D. Rousseau "FABLE 1. Synthetic description of biogeography from the approaches to the aims of studies. Comparison between the descriptive and thc causal biogeographies (modified from Dommergues and Marchand, 1988) DESCRIPTIVE BIOGEOGRAPHY CAUSAL OR EVOLUTIVE BIOGEOGRAPHY PHENETIC B. ECOLOGICAL B. ECOLOGICALB. HISTORICAL B. kPPROACH no ecological or synecological autecological morpho-functlonal narrative analytical historical approach =ROCES Quantitative Qualitative Eclectic Eclectic ] Hypothetico-deductive Eclectic Hypothetico- -SES deductive METHODS automatical Mapping and Mappingand Mapping and inventory of taxa with similar morphc Inventory of taxa connected treatments inventory inventory inventory -functional adaptations (morphology, similarity of index taxa of communities of taxa case biology, physiology, ecology) by eclectic by eclectic or indexes by case systematic cladistic systema expert systems tic ANALYTIC Comparison analyses of distribution of distribution of Hierarchical organization and compa- study case by compared study WAY and I~cal congruent communities in taxa in rison with the environmental data case of the pat of the patterns o ;of distributions distributions relation with environmental ~)jsoersal cen. distribution. stresses ter hypothesis Vicariant hypo- thesis AIM OF Comparison Definition of Hierarchical or- Research of the BIOME$ RECOGNITION BIOTAS RECOGNITION ;TUDIES be~een(bio) (bio)geogra- ganization of the morphofunctio, recognition and definition of commum recognition and definition of com- geographical phical areas communities and nal stresses in ties with a similar morpho.functlonal munities with a similar geological units the ecological relation with adaptations and evolutionary history stresses ecological con- ditions spatio-temporal fac- partly by vica only by vicarian tor taken into accoun~ cariant and di,' events :pan- or persal events phylogenetic biogeography These concepts correspond to a special approach controls, such as environment, climatology, or connec- which does not take into account the temporal factor tions between land masses, which may be confirmed by but favours an instantaneous ecological one. Such other earth sciences (Table 1). works have always had a descriptive hard core, but in This approach is well developed in a recent faunistic the view of Craw and Weston (1984) they are not an and systematic review by Solem (1984). He proposed a appropriate basis for research. generalized world model of land snail diversity and abundance. First he cited the example of the highest Causal or Evolutionary Biogeography diversity of land snails in the mid-North island of New Unlike the methods previously discussed, this Zealand and proposed arguments to explain such approach seeks to establish the distribution of living diversity. Then using that example, he attempted to organisms, but also to understand it from an historical explain the diversity of land snails in the major recent point of view, proposing hypotheses which may be biomes. He illustrated the temporal aspect of diversity confirmed by data provided by other sciences: for with, for example, the Miocene of Kenya and the example tectonics or climatology. Data sets can be Pleistocene of Europe. considered according to an ecological (Blondel, 1986) Second, historical causal biogeography. The or historical time perspective (Table 1). approach is either narrative or analytical, that is to say First, ecological causal biogeography. Although the that the process is eclectic in the former case and approach is morpho-functional, the process can be an hypothetico-deductive in the latter. Differentiation eclectic or hypothetical-deductive one. The methods exists in the method used: in the former case, an are similar: the establishment of an inventory of taxa inventory of taxa is related to Simpsonian systematics; showing one or more similar morpho-functional adap- in the latter, the taxa are related to phylogenetic tations (morphology, biology, physiology, ecology), systematics. The analysis by the narrative process which are compared with environmental data. The aim consists of a case by case study of the patterns of in the former case (eclectic) is to recognize and define distribution compared with a dispersal centre hypo- communities and their variations through time accord- thesis. In the analytical processes, the analysis is made ing to known data about the environment. In the latter by a congruent study of the patterns of distribution with case, the environment does not explain